CHANGES IN THE QUANTITY AND STRUCTURE OF EPICUTICULAR WAXES IN ECOTYPES OF Trichloris crinita UNDER WATER STRESS.

FIORETTI, M.N.; BAIONI, S.S.; BREVEDAN, R.E.

Tandil, Argentina

Congreso; X Congreso Argentino de Ciencias Morfológicas; 2006

The nature of changes of the epicuticular waxes depends on the intensity and duration of the stress so much as in the genetical ability to face up the harshness of the environment. The structure, layout and quantity of epicuticular waxes in  ecotypes of Trichloris crinita (Ñacuñán (Ñ), La Jarilla (J), El Retamo (R), La María (M), Loventue (L), La Araña (A)) adapted to sites of contrasting moisture availability were studied to evaluate the variation of those parameters under a severe water stress. Plants were grown in the greenhouse. Treatments were: control (plants kept at field capacity) and stress (irrigation was suspended during 45 days). Waxes were quantified gravimetrically after dilution with Cl4C. The adaxial and abaxial surfaces of the leaves were observed with a scanning electron microscope. In general, there was a large deposition of wax in the stress. The wax quantity of J and A under stress was greater than in the control (132 and 145%, respectively). In the stress treatment of Ñ leaf wax doubled the content of the control, but that quantity was lower than the control of other ecotypes. There were no major deposition of wax in R, M and L under water stress. The deposition of waxes was disposed as a reticulate thread with the exception of A that under stress showed atypical wax structures and M that presented differencies in both leaf surfaces. Longer threads than the previous described were covering the stomata, perpendicularly to the stomatal pore.